After a five-hour packed public hearing, the board of Silicon Valley’s largest water provider postponed a decision on whether to provide up to $650 million toward a $17 billion plan to build two giant tunnels under the Sacramento-San Joaquin River Delta to move water south.

Although it appeared there might be four votes on the seven-member Santa Clara Valley Water District board in favor of Gov. Jerry Brown’s so-called WaterFix project, board members late Wednesday night were divided and continued the issue until Tuesday at 9:30 a.m. In October the board unanimously voted against the plan over environmental concerns and potential higher costs for customers who would see little benefit from the project.

At least three said that given the risk that ratepayers will bear the brunt of likely cost overruns on a project of such a large size, they needed more time to read and understand hundreds of pages of staff reports and draft contracts, some of which were presented to them only 24 hours earlier by district staff members urging them to approve the plans.

“What’s the rush?” said Dick Santos, chairman of the water district board. “In my opinion, we need to sit down as a group and really discuss these things. This is too fast.”

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Brown’s plan calls for building two massive tunnels, each four stories high and 35 miles long, under the Delta. Supporters, who include business groups and Los Angeles-area water agencies, say the project would give cities and farms a more reliable water supply by reducing reliance on giant pumps near Tracy. In recent years those pumps have been ordered shut down by court rulings at times to protect endangered salmon, smelt and other fish.

Critics, including most of the state’s environmental groups and Northern California congressional representatives, have compared the project’s risk of cost overruns to Brown’s high-speed rail project and worry that it would make it easier for Southern California interests and Central Valley farmers to take more water from the north, despite promises to take only the current amount from the Delta.

In a letter, Rep. Anna Eshoo, D-Palo Alto, urged the board to delay reconsideration or to reject the tunnels plan. She cited concerns about the price tag, which water district staff said would increase rates by up to $10.26 per month by the time the tunnels are operational in 2033.

“In my view, WaterFix remains plagued by high costs and mismanagement that justified the board’s prior rejection of this project, and it’s unclear what has changed in the last six months to ensure that it now meets the criteria the board put forth last October,” Eshoo said.

Several board members who voted against the two-tunnel plan in October said Wednesday that they changed their minds after the powerful Metropolitan Water District of Southern California, which has 20 million customers, voted to contribute $11 billion to the project last month. They said that they wanted Santa Clara Valley Water District to participate in a joint powers agreement with the Los Angeles-based agency to help build the project so it would have a seat at the table.

“It’s important that we stay engaged. I do not trust Southern California and agribusiness to be looking out for the interests of Northern California,” said board member Barbara Keegan.

But board member Linda LeZotte said she had concerns about the project’s environmental impacts on fish, wildlife and water quality in the Delta and San Francisco Bay. Other board members said they are worried about construction problems that could mean property tax increases or higher water rates in the event of cost overruns.

“The cost I don’t believe for a minute,” said LeZotte. “I have concerns about the environment, and I don’t see the need for two tunnels. On the other hand, Met has put us in a position where we need to be at the table. I’m highly conflicted.”

The project already has been hit with multiple lawsuits and still needs approval from the State Water Resources Control Board. Brown has only eight months left in his term to try and pull it across the finish line; none of his potential successors have indicated strong support for the two-tunnel plan.

Throughout the evening Wednesday, more than 40 members of the public spoke, most in opposition. Union members in orange T-shirts said the project would bring construction jobs. Environmental groups said it was a boondoggle.”

FILE – In this Feb. 23, 2016, file photo, a sign opposing a proposed tunnel plan to ship water through the Sacramento-San Joaquin Delta to Southern California is displayed near Freeport, Calif. (AP Photo/Rich Pedroncelli, File)

One of the state’s top water officials, Karla Nemeth, a former Metropolitan Water District employee whom Brown appointed several months ago to run the state Department of Water Resources and oversee the project, drove to San Jose for the meeting.

“As I’m sure you all know, the vote before you today is part of a transformational moment in California water policy,” Nemeth said. “The choices and outcomes are as meaningful and as consequential tonight as those made by water managers who built the State Water Project decades ago.”

The Santa Clara Valley Water District, which provides water to 2 million people, is considered a key player in the tunnels debate because its support would allow Brown and other supporters to frame the issue as a statewide one, rather than a north-south battle. The proposed Peripheral Canal plan in 1982, when Brown was also governor, was defeated by voters in a statewide ballot measure after the issue broke down as a battle between north and south over water.

In recent months, the CEO of the Santa Clara Valley Water District, Norma Camacho, and other top staff have met with Brown administration officials to discuss the tunnels project. At the same time, the district applied for $485 million in state bond funds to help it construct a new $1 billion dam near Pacheco Pass. In February, the California Water Commission, whose nine members are appointed by the governor, recommended no funding for the Pacheco Dam. But two weeks ago, the agency’s staff recommended the project receive full funding as part of an appeals process, and days afterward, the district staff placed a re-vote on the tunnels before the board.

Lisa Lien-Mager, a spokeswoman for the state Natural Resources Agency, said there was no quid pro quo deal.

“Those processes are completely separate, and suggesting otherwise is really misleading,” she said. “The Water Commission staff has been completely transparent about its review of the Pacheco project.”

District chairman Santos suggested that his agency wait to take a final vote until after July, when the state water commission board has made its final decision on using bond funds for the dam project. He said that waiting would help give the agency a better overall budget picture as it decides whether to spend $650 million on the tunnels.

But board members who said they now support the tunnels, including Tony Estremera and Gary Kremen, said they oppose that kind of delay.

Referring to Metropolitan Water District, Estremera said: “They are going to do what they want to do. They are going to do the project. Do we want to participate or not?”

Paul Rogers has covered a wide range of issues for The Mercury News since 1989, including water, oceans, energy, logging, parks, endangered species, toxics and climate change. He also works as managing editor of the Science team at KQED, the PBS and NPR station in San Francisco, and has taught science writing at UC Berkeley and UC Santa Cruz.

Jason Green is a breaking news reporter for the Bay Area News Group. He works week nights and spends most of his time covering crime and public safety. A graduate of UC Santa Barbara and the University of Southern California, he cut his teeth at the Inland Valley Daily Bulletin and the Palo Alto Daily News, and has been with the Bay Area News Group since its inception.